Examples of known compounds in which the 1-position of a decalin ring and the 3-position of 2-pyrrolidone are bound via carbonyl include ZG-1494α having a platelet-activating factor acetyltransferase inhibitory activity which is represented by formula (II): (J. Antibiotics, 49, 967-973 (1996)), oteromycin having an endothelin receptor antagonistic activity which is represented by formula (III): (J. Org. Chem., 60, 7040-7042 (1995)) and the like.
Examples of known compounds having a pyrrolizidinone skeleton include pyrrolam A represented by formula (IV): (Liebig. Ann. Chem., 525-530 (1990)), compounds represented by formulae (V) to (VIII) (Liebig. Ann. Chem., 381-385 (1988)) and the like, but antibacterial and antitumor activities are not known in each of the above-mentioned compounds.
As a compound having antibacterial activity, F-12434 represented by formula (IX): is known (Japanese Published Unexamined Patent Application No. 227514/97), and, as compounds having antibacterial activity and antitumor activity, UCS 1025A represented by formula (X) wherein R is hydrogen and UCS 1025B represented by formula (X) wherein R is hydroxy: are known (Japanese Published Unexamined Patent Application No. 245385/98).